Replaced Dash Harness - truck wouldn't start

[jaros44sr]

Keep going Looks Deceivin', I got the exact same situation in my truck, green cowl, B&M shifter, prior manual switched to auto, heck I had to go downstairs to make sure you weren't workin' on my truck

Can't ya just hook up your NSS off of the B&M shifter to the purple wires? I'm watchin' for your answers, thanks

[70rs/ss]

The purple wires are OE and are the NSS for an auto, the standard version is different, but the same, there is a switch that sits near the clutch, when you press the clutch down it closes the switch and allows the starter to engage. Just look for a plug that you didn't plug anything into on the "new" harness and that is more than likely the one. It will be an open circut which is why the truck doesn't do anything when you turn the key. You can do this, just do the one plug swap and take your time.

[70rs/ss]

Heck I just reread your post, the purple wires and that plug are the reason it didn't start. If it wasn't plugged in then the power can't get to the starter. Cut the plug off and connect the wires to gether. The Blazer was a manual trans truck so the PO rigged an auto NSS useing the starter power wire (purple wire as well but under the hood) so it will continue to work as it does now even with the new harness inside. Man, I think I just fixed it?? Did I??

[lks dcvn]

1st thing - Thx everybody for helping me with this issue - what a PITA!

When it cools down here a bit (90+ today here in Toledo) - and I get some time - it took me about 2 hours to remove/replace the harness the first time so it should take a lot less this time now that I know what to look out for...

I will add a jumper wire between the two purple ones to test...(I hate cutting up stock wiring if I don't have to) - one of the POs didn't have an issue with that (not referring to you Bouncy - )

I also got the oil pressure line fixed for the time being - had to buy a line repair kit from AutoZone - I would like to switch over to a braided line at some point - but wanted to get this line to stop leaking for the time being (Thx to GMCPaul for the tips).

I will keep you posted...

[70rs/ss]

If the harness you have in there now doesn't have the purple wires, I am just about 99.9% sure that is why it didn't work before. The PO probably already spliced the clutch safety switch when he converted to the NSS rig job for the auto shifter. I run those copper oil pressure lines in every older vehicle I own and have never had a problem, so unless you just want the bling of the $$$ braided line, I would just stick with the copper tubing, heck nobody is going to get under your dash to see it anyways, right?! Good Luck, and I am sure you have this whipped now.

[lks dcvn]

Not that you guys care...but I braved the heat tonight and set a new record for replacing the dash harness (being extra careful of the oil pressure line) - removal/install 'better' one and route - 45 mins.

And after installing the 'replacement' dash harness to the firewall harness and the ignition switch (oh and jumping the purple wires) - the thing turned over...

I then wondered if something else on the harness was going to give me trouble so I finished up the install and had to replace/splice the dimmer switch since the connection on the 'better' harness had broken, rusty terminals from the truck it was taken from.

I put the whole thing back together and checked everything out-

still starts - check
lights/brights - check
signals - check
brake lights - check
hazzards - check
dash lights - nope

Then I remembered that I didn't hook up the gauge wiring harness - hooked it up - I had lights - AND to my surprise - my stupid gas gauge works now (that was last Friday's project - replaced lines, sending unit, etc. - still didn't work) - so this harness has been quirky since I bought the truck - the gas gauge never did work - and NOW it does!

I had siphoned most of the gas out of the tank since I wasn't sure if I would have to drop the tank again to get to the sending unit - so I added a few gallons from my siphon tank - and then I went for a joy ride at dusk with my girlfriend.

Everything works as it should - wiring-wise - for now-

Still need to figure out why my reverse lights were always on with the old harness - something new to troubleshoot - maybe I should put the bulbs back in and see if they still stay on - (I will try that over the weekend).

And get the horn working - that never worked either since I got it...

A HUGE thanks to everybody - and especially Musclerodz and 70rs/ss - the jumping of the purple wires brought it back to life...here are some pix...

In order (top to bottom):

dash wiring when I got it (yes I am serious)
dash wiring when I got it - part 2 (still serious)
dash wiring (before replacement) on Sunday - attempt 1 (what a mess)
all gone - wow - a LOT cleaner looking
Old harness - finally removed - yikes!

More pix in the next post...

[lks dcvn]

More Pix!

New Harness - ready to go in
New Harness Installed - testing what worked
New Harness Installed 2 - No More Mess!
Fuel Gauge works NOW! -

Thanks again everybody - I can't tell you how glad I am the wiring fiasco is now behind me.

I think I lost 5 pounds of water - in was in my shirt since it was so muggy outside!

[lks dcvn]

Gas Tank Sending unit project from last Friday...

In case you wanted to see the pix...

Old Lines - one leaked from rubbing
Old Sending unit
Old vs New Sending Unit
New Lines/Clamps

[Yukon Jack]

Glad you got it figured out! I hate working in the heat too! My favorite time to wrench is when winter.

[bouncytruck]

Wow, looks great now. Glad you got it working again. I always wanted to replace the wiring in that truck. I did put a better engine compartment harness in. It was just as bad as the mess under the dash, but it had several live wires just hanging inside the engine bay.

Man, that sending unit was in bad shape. It makes me wonder what the sending unit in my tank looks like - it is only a couple years newer than yours. That might be a "to do" project. I never would have guessed the gauge issue was in the dash harness.

[lks dcvn]

Bouncy - after I dropped the tank, checked the grounds and replaced the sending unit and the fuel gauge still didn't work - I knew the dash harness might be the culprit - that was the only option left...

I spent 8 hours working on replacing that tank (never knew how much was in the there) - I bought two 5 gallon gas cans to hold the siphoned gas - turns out there was a lot more than 10 gallons - I put gas in the lawn mower, the beater, my Yukon...then it finally ran dry - (thankfully). Most of the time was spent siphoning the gas and then trying to drop the tank from between the exhaust routing - PITA pt. 2.

Nice to see that thing (gas gauge) work now - it makes it a lot easier on the mind to have an idea of how much gas the thing has in it...

I was pleased with the wiring clean-up but the fuel gauge working - icing on the cake -

[70rs/ss]

I'd bet the back up lights issue is the hacked wiring to the floor shifter. The lights need to be wired into the Reverse switch on the shifter (may need to get the switch first!) then wire the rear lights into that. In a stock auto console the switch would be on the colum and when in reverse, the shift rod has a cam on it to engage the back-up lights switch (wiring will be there on the auto wiring harness, just run some jumpers from the OE plug to the switch). Just need to get the switch on the floor shifter wired into the factory harness.

Glad I could help ya, I love to help solving other member's issues, cause 1) I can't work on my junk since the surgery, and 2) If I can't figure it out, Oh Well, its not mine!! Just kidding!! It is actually easier for me to help trouble shoot for some else, because I get so disgusted with my stuff I can't think straight.

I am problem solver, that's why I have a tough time with the ladies, I am not a listener, I am a fixer, if I am told something by my wife I fix it even if she just wanted me to "listen" anyone else have that!?

[Jtrux]

I don't know if you said this or not but what harness did you go with?? And cost too if you don't mind saying.

[lks dcvn]

I actually found the used OEM dash harness on Craig's List - somebody in Iowa was parting a truck and it had a VERY clean dash harness - only one splice in the radio wire...

Turns out the dimmer switch (on the floor) was corroded on the better harness and had rusted terminals in it that were seized so I cut the dimmer from the old harness and used that one in the truck.

The dash harness was $30 shipped last year...

I have been picking up used harnesses for the dash specific connectors (backups) in case I should need a replacement.

I have spent several hundred on this truck - and the replacement of the dash harness was the best money I have spent so far...

70rs/ss - agree on the wiring to the floor shift - just haven't got time to work on the Blazer - trying to get the other project done -

**Just noticed that Jtrux is in San Antonio - I will be in SA in November for a week - doing a bit of sightseeing with the girl. One day we will be checking out Austin as well.

[Long Roof]

Originally Posted by 70rs/ss

I am problem solver, that's why I have a tough time with the ladies, I am not a listener, I am a fixer, if I am told something by my wife I fix it even if she just wanted me to "listen" anyone else have that!?

You must be the first guy to ever have that problem. It surely *sigh* has never happened to me

(I only listen long enough to come up with a solution to the problem. It has NEVER been what she wants to hear)

[Jtrux]

Originally Posted by lks dcvn

**Just noticed that Jtrux is in San Antonio - I will be in SA in November for a week - doing a bit of sightseeing with the girl. One day we will be checking out Austin as well.

If you need any tips on where to go for sight seeing let me know, I know where to go. And if you want to see some blazers I know where to go for that too. We'll tell your girl that we're going to see some really cool historical stuff then pull up to a field where some rusty blazer is sitting. Can't beat that.

Oh and btw, great deal on the harness. A parts truck that I have has a really clean harness too, I was just looking at it today. Maybe it will find it's way into my blazer, I do need the AC portion of it anyways since i'm transplanting all AC stuff into my blazer from that truck.

[70rs/ss]

Originally Posted by Long Roof

You must be the first guy to ever have that problem. It surely *sigh* has never happened to me

(I only listen long enough to come up with a solution to the problem. It has NEVER been what she wants to hear)

^^^^^DITTO^^^^^ Never what she "wants to hear?" Reminds me of the Andrew "dice" Clay line, I just wanted to be held....Well, you got the bonus package!!